Cutting thin layer(s) from semiconductor material(s)

ABSTRACT

An apparatus for cutting at least one thin layer from a substrate or ingot forming element for an electronic or optoelectronic or optical component or sensor. This apparatus includes a device for directing a pulse of energy into the substrate or forming element wherein the pulse has a duration shorter than or of the same order as that needed by a sound wave to pass through the thickness of the weakened zone, and the energy of the pulse is sufficient to cause cleavage to take place in the weakened zone as the energy of the pulse is absorbed therein. The apparatus also includes an assembly for holding or orienting the substrate or ingot forming element so that the energy pulse is completely uniformly directed over the entire surface, through the face and into the substrate or ingot forming element to cause cleavage to take place in the weakened zone as the energy of the pulse is absorbed therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 10/268,776 filedOct. 11, 2002, now U.S. Pat. No. 6,951,799, which is a continuation ofInternational application No. PCT/FR01/01179 filed Apr. 17, 2001,theentire content of each of which is expressly incorporated herein byreference thereto.

BACKGROUND ART

The invention relates to cutting at least one thin layer from asubstrate or ingot, in particular of semiconductor material(s), formaking an electronic, optoelectronic or optical component or sensor.

In numerous applications associated with the fields of microelectronics,optoelectronics, and sensors, the technological operation oftransferring a layer of one substrate onto another represents a keyoperation that enables numerous materials structures or specificcomponents to be fabricated. The layer for transfer may or may notinclude components that are complete or in a partial state ofcompletion.

One example of such applications is in making silicon on insulator (SOI)substrates. Typically, the insulator used is SiO₂ of amorphous structureon which it is not possible to deposit silicon of monocrystallinequality. One category of techniques for making such structures relies onmolecular adhesion techniques referred to as “wafer bonding”. Thesetechniques are known to the person skilled in the art and in particularare described in the text “Semiconductor Wafer Bonding Science andTechnology” by Q. Y. Tong and U. Gösele, a Wiley IntersciencePublication, Johnson Wiley & Sons. Inc. As described in that text, usingsuch techniques, two substrates (generally silicon substrates) areassembled together, one that is used to form the SOI layer (the “source”substrate) that is to be transferred onto the other substrate. Thisother substrate thus becomes the new “support” substrate that supportsthe SOI layer. A layer of insulation, typically of SiO₂ is previouslyformed on at least one of the faces of the substrates prior to assembly,thus obtaining a buried insulator situated beneath the SOI layer.

Certain variants are known as “bonded SOI” (BSOI) or indeed “bond etchback SOI” (BESOI). In addition to molecular adhesion, these variantsrely on physically removing the source substrate either by techniques ofthe polishing or mechanical lapping type and/or by techniques of thechemical etching type. Other variants rely on splitting along a zone ofweakness in addition to molecular adhesion on separation. These methodsare described in U.S. Pat. No. 5,374,564 (or EP-A-0 533 551) and U.S.Pat. No. 6,020,252 (or EP-A-0 807 970) where splitting occurs along aweakened zone of implanted ions, or in European patent application 0 925888, where splitting occurs through a buried layer that has been madeporous.

Those layer transfer techniques present are of a generic nature sincethey enable structures to be made that combine various types of materialwith one another, and specifically that they enable structures to beobtained that are not possible to make otherwise, and in particular bydeposition. Examples are monocrystalline silicon substrates on quartz,AsGa substrates on silicon, and the like.

The advantage of the methods that split along a buried fragile layer isthat it is possible to make layers based on crystalline silicon (or onSiC, InP, AsGa, LinbO₃, LiTaO₃, and the like) in a range of thicknessesthat extends from a few tens of angstroms (Å) to a few micrometers (μm),with very good uniformity. Even greater thicknesses are possible. otherexamples of applications in which layer transfer techniques can providea suitable solution for integrating components or layers on a supportthat would otherwise be unsuitable for receiving such components orlayers. These layer transfer techniques are also very useful when it isdesired to isolate a fine layer, with or without components, from itsinitial substrate, e.g., by separating or eliminating the substrate.

By way of example, more and more components are expected to beintegrated on supports that are different from those which enabled themto be made. By way of example, mention can In addition to makingsubstrates, there are numerous be made of components on substrates madeof plastics or on substrates that are flexible. The term “components” isused herein to mean any microelectronic device, optoelectronic device,or sensor device (e.g. a chemical, mechanical, thermal, biological, orbiochemical sensor device) that is fully or partially “processed”, i.e.that has been made in full or in part. In order to integrate suchcomponents on flexible supports that are otherwise incompatible withsuch components, it is possible to use a layer transfer method which isperformed after the components have been made on a substrate which iscompatible with them.

Still in the same spirit, turning a fine layer over while transferringit to another support provides engineers with a degree of freedom thatis very useful for designing structures that would otherwise beimpossible. Taking and turning over such thin films make it possible,for example, to make so-called “buried” structures such as buriedcapacitors for dynamic random access memories (DRAMs) where, contrary tothe usual case, the capacitors are made first and then transferred ontoanother silicon substrate, after which the remainder of the circuits arefabricated on the new substrate. Another example lies in themanufactures of double gate transistors. The first gate of a CMOStransistor is made using conventional technology on one substrate, andit is then turned over and transferred onto a second substrate where thesecond gate of the transistor is made and the transistor is finished,thus leaving the first gate buried within the structure (see for exampleK. Suzuki, T. Tanaka, Y. Tosaka, H. Horie, and T. Sugii, “High speed andlow power n+-p+ double gate SOI CMOS”, IEICE Trans. Electron., Vol.E78-C, 1995, pp. 360–367).

An identical situation is to be found for example in the field ofapplications associated with telecommunications and microwaves. Undersuch circumstances, it is preferable for components finally to beintegrated on a support presenting high resistivity, typically severalkilo ohm-centimeters (kΩ·cm) at least. However a highly resistivesubstrate is not necessarily available at the same cost and quality asthe standard substrates that are usually used. With silicon, siliconwafers having a diameter of 200 millimeters (mm) and wafers having adiameter of 300 mm are available at standard resistivity, whereas forresistivities greater than 1 kΩ·cm availability is quite inadequate at200 mm and non-existent at 300 mm. One solution consists in making thecomponents on standard substrates and then in transferring them duringthe final stages to a fine layer containing components on an insulatingsubstrate of glass, quartz, sapphire, or the like.

From a technical point of view, these transfer operations have the majoradvantage of de-correlating the properties of the layer in which thecomponents are made from those of the final support layer, andconsequently they are advantageous in many other circumstances.

Relating more specifically to layer transfer techniques based on thesplitting (i.e., breaking or separating) along a zone of weakness(“weakness” to be understood broadly and from a mechanical point ofview) or a zone predefined to originate separation selectively (e.g.,separation by chemical etching), several techniques are known concerningthe step or combination that gives rise to the cut.

For example, certain combinations are based more specifically onmechanical separation (e.g., the high pressure water jet disclosed in EP0 925 888). Certain techniques based on the so-called “lift-off”principle also enable a thin layer to be separated from the remainder ofthe initial support, without necessarily consuming it. Those methodsgenerally make use of chemical etching that acts selectively on a buriedintermediate layer, optionally associated with the application ofmechanical forces. That type of method is in widespread use fortransferring III–V elements on to various types of support (see C.Camperi et al. IEEE Transactions and Photonics Technology, Vol. 3, 12(1991) 1123).

As another example, EP 0 925 888 describes slitting by means of afracture along a buried layer that is made porous by mechanical meansrepresented by a jet of water under pressure applied in the vicinity ofthe zone to be cut. A jet of compressed air can also be used asdescribed in French patent application FR 2 796 491, or it is alsopossible to exert traction as disclosed in PCT published application WO00/26000. It can also be appropriate to insert a blade.

Other examples rely on a zone of weakness obtained by implantation. Acut can be obtained along this zone of weakness, optionally by combiningsaid implantation with the specific means for applying mechanical forcesas mentioned above (or other such means) and/or chemical etching and/orheat treatments, etc. A few examples of such techniques are to be foundin documents U.S. Pat. No. 5,374,564 (or EP-A-0 533 551) and U.S. Pat.No. 6,020,252 (or EP-A-0 807 970), and PCT published application WO00/61841.

Numerous means can be adopted to trigger or assist splitting along azone of weakness. U.S. Pat. Nos. 6,020,252 and 6,013,563 and Europeanpatent applications 0 961 312 and 1 014 452 provide more detailedexplanations of, for example, mechanical forces in tension, in shear, intwisting, heat treatments using a wide variety of hot or cold sources ofheat (conventional ovens, light means, lasers, electromagnetic fields,electron beams, cryogenic fluids, etc.), laser ablation of anintermediate layer, and the like.

The layer transfer techniques mentioned in the introduction neverthelesspresent certain specific drawbacks.

Techniques based on thinning down (mechanically, chemically, etc.)suffer from the drawback of consuming and sacrificing a substrate, whichis inefficient from an economic standpoint. Such thinning techniques arealso often quite difficult and expensive to implement.

Combinations based on applying external mechanical stresses (shear,twisting, bending, tension, and the like) suffer from the drawback ofgenerally requiring adhesion (molecular or otherwise) that issufficiently strong to avoid breaking under the stress needed forrupturing the weak zone. A method for obtaining such adhesion is notalways available in certain manufacturing methods or applications whichare subject to very severe specifications (e.g., where it is impossibleto heat, impossible to use specific solvents or other chemicals,impossible to apply traction to the structure because of the risk ofdestroying sensitive components, etc.).

In certain applications, techniques based on annealing and other heattreatments come up against incompatibility with the step of raisingtemperature, e.g., the temperature of the final support on which thelayer is to be integrated. For example, the new support may not becapable of withstanding the temperatures required. This generallyapplies to plastic materials. By way of another example, theincompatibility can stem from the combination of materials, inparticular because they have too great a difference in thermal expansioncoefficients which would cause an assembly that is not sufficientlyuniform to break during a temperature rise. This would apply for exampleto a structure that combines silicon and quartz.

Techniques based on chemical etching are aggressive and this can makethem incompatible with the final support on which the layer for transferis to be integrated, or with components that might already be present onthat layer.

Among other combinations, U.S. Pat. No. 6,013,563 and European patentapplication 1 014 452 describe or mention techniques based on applyingbeams of light and/or electrons. U.S. Pat. No. 6,013,563 refers toapplying a beam of photons and/or electrons in order to heat thestructure, while EP 1 014 452 describes a method in which an arbitrarysource of photons (X rays, UV light, visible light, infrared light,microwaves, lasers, etc.) is suitable for giving rise to separation. Theimplementation described when using a laser, for example, refers tolaser ablation of the intermediate layer which leads the authors toprefer using laser pulses of relatively high power (“preferably forenergy densities lying in the range 100 millijoules per squarecentimeter (mJ/cm³) and 500 mJ/cm³”) and of relatively long duration(“preferably for durations lying in the range 1 nanosecond (ns) to 1000ns, and especially for durations lying in the range 10 ns to 100 ns”).The authors also state that that method of implementation requiringrelatively large amounts of energy to be delivered in order to operatesuffers from the drawback of possibly damaging the layer that is to betransferred.

Thus there is a need for further manufacturing processes that do notpossess the disadvantages of the prior art.

SUMMARY OF THE INVENTION

The present invention provides a new method of cutting a semiconductormaterial along a zone of weakness which does not rely on raisingtemperature, chemical etching or decomposing the layer of weakness(whether by ablation or otherwise). In this method, a layer of weaknessis cut by injecting a pulse of energy into the substrate so as togenerate a sound wave of amplitude suitable for causing cleavage to takeplace in the layer of weakness.

The invention specifically relates to a method of cutting at least onethin layer from a substrate or ingot forming element for an electronic,optoelectronic or optical component or sensor. This method comprisesforming a weakened zone in the substrate or ingot forming element,wherein the weakened zone has a thickness that corresponds to that ofthe layer that is to be removed; and generating and directing a pulse ofenergy into the substrate or forming element wherein the pulse has aduration shorter than or of the same order as that needed by a soundwave to pass through the thickness of the weakened zone. The energy ofthe pulse is sufficient to cause cleavage to take place in the weakenedzone as the energy of the pulse is absorbed therein.

In this method, the weakened zone can be a porous zone, in particular,one formed by deposition or by implantation. When implantation is used,the implantation is of phosphorus, arsenic, protons, or rare gas ions.Also, the substrate or ingot forming element advantageously comprisessemiconductor material(s), LiNbO₃, LiTaO₃, or a composite materialthereof. Especially preferred are Silicon, SiC, GaAs, InP, GaN, SiGe,Ge, LiNbO₃, LiTaO₃, or a composite material thereof.

After the weakened zone forming step, the substrate or ingot formingelement is generally bonded onto a support to form a block. When this isdone, the energy pulse is directed into the block. The block can beformed by bonding the substrate or ingot forming element onto thesupport by molecular adhesion bonding or by adhesive bonding. Ifdesired, the block can include a layer of SiO₂, Si₃N₄, or a combinationthereof.

The energy pulse is preferably generated by a laser beam, although italso can be a beam of electrons. The energy pulse is of short durationso as to not cause heating of the block. Generally, a duration of lessthan 1 ns is used. The energy pulse may be a single pulse or repeatedmultiple times, as necessary to cause cutting of the layer.

In one embodiment, the substrate or ingot forming element has a polishedface and the energy pulse is directed through that face and into thesubstrate or ingot forming element. When implantation is used to providea weakened zone, the energy pulse can be directed into the substrate oringot forming element through the same face as the implanted ions, orthrough a second face that is on an opposite side of the substrate oringot forming element.

In a preferred embodiment, the energy pulse is directed to beselectively absorbed directly on the weakened zone. The substrate oringot forming element can be doped so that the energy pulse isselectively absorbed in the weakened zone. If so, the doping preferablyincludes ionically implanting phosphorus or arsenic into the substrateor ingot forming element. The selective absorption can be performed in ametal layer, or within a deposited layer. Typically, the selectiveabsorption is obtained within a layer whose properties have beenmodified by implantation.

The energy pulse may be directed onto the substrate or ingot formingelement after all or part of a component of an electronic,optoelectronic or optical component or sensor has been made.

In this regard, the invention also relates to a method of making anelectronic or optoelectronic or optical component or sensor whichincludes a method of cutting at least one thin layer from a substrate oringot forming element according to the methods disclosed herein.

The invention also relates to an apparatus for carrying out thesemethods. This apparatus comprises means for generating and directing apulse of energy into the substrate or forming element wherein the pulsehas a duration shorter than or of the same order as that needed by asound wave to pass through the thickness of the weakened zone, and theenergy of the pulse is sufficient to cause cleavage to take place in theweakened zone as the energy of the pulse is absorbed therein.

The energy pulse generating means preferably comprises a YAG or aneodymium-doped glass laser suitable for delivering pulses that have aduration of less than 1 ns. It may comprise a laser or a sheet of solidlasers, or a pulsed diode type pulse accelerator for delivering a beamof electrons that have a duration of less than 1 ns.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The characteristics and advantages of the invention appear better fromthe following description referring to the accompanying figures inwhich:

FIGS. 1 a and 1 b are cross-sectional views taken through the set ofsemiconductor and insulating substrates after implantation (FIG. 1 a)and bonding (FIG. 1 b);

FIGS. 2 a and 2 b are graphs showing the relationship for energydeposited in the material when the energy is deposited with a laser;

FIG. 3 is a graph that shows a sound wave at a given instant in the formof a curve P(x);

FIG. 4 is a graph that shows the sound wave behind a break in materialin the form of the relationship P(x);

FIG. 5 illustrates an apparatus for depositing energy by laser pulse;and

FIG. 6 illustrates an apparatus for depositing energy when using anelectron beam to heat the surface layer of a semiconductor substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred first implementation of the invention, the procedure isas follows. The starting material is a semiconductor wafer, e.g. ofsilicon 2 (see FIG. 1) having a thickness of about 500 μm, which ispolished on one of its faces 1. Protons are implanted in its face at anenergy such that their penetration depth into the semiconductor is alittle greater than the thickness λ of the thin layer of semiconductorthat is to be made. For example, to make a layer that is about 1 μmthick, protons are used at an energy of about 150 kilo-electon volts(keV).

Thereafter, an insulating substrate 4 is prepared, and in the exampleshown in FIG. 1 this is a substrate of silicon covered in a layer ofSiO₂ having a typical thickness of a few tenths of a micrometer.

Thereafter, the substrates (4 and 2) are bonded together by molecularadhesion using a method that is now well known (see for example the text“Semiconductor wafer bonding Science and Technology” by Q. Y. Tong andU. Gösele, a Wiley Interscience Publication, Johnson Wiley & Sons.Inc.).

This produces the block shown in FIG. 1 b. This block is then impulseheated from the free surface of the semiconductor wafer 2, i.e., theface 13 shown in FIG. 1 b. The purpose of the heating is to raise thepressure in the thickness ε₀ affected by the heating, with this beingnecessary in order to generate the sound wave that is to be used forbreaking the implanted layer 7 that is weakened by implantation or byany other means. To heat the layer of thickness ε₀ beneath the surface13, it is necessary to implement or come close to implementing “constantvolume heating” conditions. Heating causes expansion, but this can occuronly in the form of a sound wave propagating at the speed of sound. Ifthe heating is performed at a time t that is shorter than the time takenby the sound wave to pass through half the thickness of the heated layer(of thickness equal to ε₀), it will readily be understood that thecenter of this layer will not be able to expand throughout the durationof the heating. Heating is thus performed at “constant volume”,providing the following relationship is complied with, where C is thespeed of sound:

$t < \frac{ɛ_{0}}{2C}$The orders of magnitude implied by this relationship are dominated bythe need to implement a sound wave that is very short inthree-dimensional space.

Specifically, it is deemed that this is satisfied when the duration ofthe energy pulse is less than or of the same order as the durationneeded by a sound wave to pass through the thickness of the zone thatabsorbs the energy of the pulse. This pulse has the requisite energy tocause cleavage to take place in the weakened zone.

In order to ensure that the rupture mechanism is effective, it isnecessary for ε₀ to be of the same order of magnitude as the thickness λof the layer that is to be detached, which is of micrometer order. It isalso known that in a semiconductor, e.g., silicon, the speed of sound isabout 2×10³ meters per second (m.s⁻¹). The above relationship thusindicates that the duration of the pulse must be of the same order as orshorter than 1 ns, and preferably less than 0.5 ns, which is extremelybrief but which can be achieved using special lasers or electron beams.

Once the above conditions are satisfied, the amplitude ΔP of the soundwave in compression or in expansion can be expressed by the Grüneisenrelation:

${\Delta\; P} = {\frac{1}{2}{\Gamma \cdot \rho \cdot \frac{\mathbb{d}E}{\mathbb{d}m}}}$where:

-   Γ is the Grüneisen constant which for silicon is about 1.5;-   ρ is the density of the medium and is about 2.5×10³ (S.I. units);

$\frac{\mathbb{d}E}{\mathbb{d}m}$is the variation in the specific internal energy of the medium. It isequal to the impulse heating per unit mass.

By way of example, it is assumed that the impulse heating gives rise toa temperature rise Δθ=75° C. in silicon having specific heat of 0.75joules per gram, which gives:

$\frac{\mathbb{d}E}{\mathbb{d}m} = {5.62 \times 10^{4}\mspace{14mu}{\left( {S.I.\mspace{14mu}{units}} \right).}}$

Inserting these values into the above equation, it is found that atypical pressure is 105 megapascals (MPa), or in other words 1.05kilobars (kbar). It should be observed that this wave amplitude, whenimplemented in the form of expansion, is of the same order of magnitudeas the cohesion strength of the material, and that it is thereforedesigned to break the layer that is weakened by ion implantation.Finally, it should be observed that such a high pressure is obtainedmerely by a modest temperature rise of 75° C. at the point where theenergy is deposited, and that as soon as this energy disperses into thethickness of the substrate, the temperature rise becomes less than 1° C.It is thus genuinely possible to speak of a “cold” method ofdelamination, i.e., one that does not cause any appreciable heating ofor damage to the material.

The sound waveform depends on how the deposited energy is distributed inthe material. If it were possible to deposit the energy in zero time andif its distribution ε(x) as a function of depth x in the semiconductor(2) were of exponential appearance as shown diagrammatically in FIG. 2a, then at the instant the pressure would be P(x) as represented by thecurve shown in FIG. 2 b. In reality, the distribution Po(x) is deformedby the prorogation of expansion throughout the duration of deposition,and is never instantaneous.

This initial pressure splits into two waves, one going rearwards (in theincreasing x direction) and the other going in the opposite direction,reflecting on the free face, and then also travelling rearwards, butthis time in the form of an expansion wave. FIG. 3 shows the completewave at a given instant during its propagation through wafer 2. It willbe observed that the total impulse, i.e., the area beneath the curve, iszero, which is necessary since the laser or electron beam responsiblefor the heating is of quasi-zero impulse. When the expansion wavereaches the implanted layer whose breaking stress is assumed to be T,then the wave as transmitted downstream is truncated, as shown in FIG.4. Thus, the impulse received by layer 2 and by its support 4 is notzero, causing the mass to be ejected at low speed.

There follows an examination of how the face 13 is impulse heated. It isshown above that the heated thickness should be about 1 μm,corresponding to a mass of material of about 2.5×10⁻⁴ grams per squarecentimeter (g/cm²). Thus, in order to achieve the above-mentionedimpulse temperature rise of 75° C., it is necessary for the energydensity of the beam to be about 1.87×10⁻⁴ J/cm². This ideal energy isvery weak. In order to separate a layer from a wafer of 300 mm diameter,it would suffice for the laser pulse or electron beam to have energy of0.13 J.

In reality, it is necessary to use much higher energy because of theexpansion which occurs while energy is being deposited and also becauseabsorption does not take place in ideal manner, i.e., it includes adistribution tail which is ineffective in raising pressure. In practice,the energy needed to separate a wafer over 300 mm diameter is about 13joules.

In order to deposit the required energy in the surface 13, it ispossible either to use a very short pulse laser such as a yttriumaluminum garnet (YAG) laser, for example, using one or two stages ofamplification and a Q-switched pilot 11 with wavefront steeping bysaturatable plates so as to achieve pulses of 0.1 ns to 1 ns duration.For higher energies per pulse, the final stages of amplification may bemade of neodymium glass. A setup of the type shown in FIG. 5 is thenobtained. A system of lenses L1, L2 serves to apodize and expand thebeam 9 so that the energy density is completely uniform over the entiresurface 13 whose diameter can be as great as 300 mm using present-daytechnology. FIG. 6 illustrates the use of a grid to expand the beam tocover the entire surface of the substrate.

Once the apparatus has been set up, the laser beam having a wavelengthclose to 1.06 μm must be coupled with the semiconductor constituting thesubstrate 2. When this semiconductor is made of silicon, if the 1.06 μmbeam were to be used directly, then absorption would take place over amean thickness of about 100 μm, which is much too great. In order toreduce the thickness of the energy deposition, it is necessary toincrease the absorption of the medium 2. This can be done by:

1) doubling, tripling, quadrupling the frequency of the laser beam usingthe now well known techniques based on non-linear effect plates;

2) surface doping, e.g. by tonically implanting phosphorus or arsenic inorder to reduce resistivity and thus increase absorption of the materialat 1 μm wavelength;

3) depositing a thin absorbent layer on the face 13, e.g. a metal layerhaving at thickness of 1 μm.

To deposit the energy, it is also possible to use a pulsed electron beam(10, see FIG. 6) obtained using a pulse diode 12. To ensure thatpenetration in layer 2 is on the order of 1 μm, the energy of theelectrons needs to be limited to about 30 keV. For a surface of 300 mmdiameter, in order to deposit energy of about 3 joules, and takingaccount of the better absorption by layer 2, the current delivered tothe diode should be 150 kiloamps (kA), which is easily achievable.

In another preferred implementation of the invention, given by way ofnon-limiting indication, energy is deposited by means of a 1.06 μm laserbeam as described above directly into the implanted layer 7 where it isdesired to cause splitting or fracture. The description relates to thecase where the semiconductor 2 is constituted by silicon. Given thatsilicon is rather transparent at the YAG wavelength, it is possible toreach the layer 7 in the center of the stack 2,4 by illuminating eitherface 13 or the opposite face of the structure. Advantage is taken of theimplanted layer being naturally much more highly absorbent than theinitial crystal, even when implantation is performed using protons. Itis also possible to increase its absorption strongly by implanting ionsof phosphorus or of arsenic or of any other suitable element. It shouldbe observed that under such circumstances, the expansion wave created isabout twice that obtained in the preceding case, other parametersremaining identical. Furthermore, implementation is simplified since itis no longer necessary to ensure that the layer where the energy isdeposited is parallel with the implanted layer since they are now thesame layer. This disposition also presents the advantage of notrequiring the bonding operation whose traction strength must be veryhigh. Each of the two portions that result from cleaving the implantedlayer 7 receives a clean impulse. In other words, the bonded interface 3is subjected only to a compression wave, providing that the faceopposite to the surface 13 has deposited thereon a mechanically matchingmedium that enables the compression sound wave to be received so that itdoes not reflect in expansion from that face. This medium or damper canbe constituted by a plate of silica having a thickness of 10 mm or 20 mmand which is permanently or temporarily bonded to the face opposite toface 13.

The invention can be used for industrial manufacture of a substrate ofthe SOI type.

1. An apparatus for cutting at least one thin layer from a substrate oringot forming element for an electronic, optoelectronic or opticalcomponent or sensor, wherein the substrate or ingot forming elementincludes a face and a weakened zone oriented substantially parallelthereto, with the weakened zone having a thickness that corresponds tothat of the thin layer that is to be removed, the apparatus comprisingmeans for generating a pulse of energy into the substrate or formingelement wherein the pulse has a duration shorter than or of the sameorder as that needed by a sound wave to pass through the thickness ofthe weakened zone, and the energy of the pulse is sufficient to causecleavage to take place in the weakened zone as the energy of the pulseis absorbed therein; and means for directing the energy pulse completelyuniformly over the entire surface, through the face and into thesubstrate or ingot forming element to cause cleavage to take place inthe weakened zone as the energy of the pulse is absorbed therein.
 2. Theapparatus according to claim 1, wherein the energy pulse includes a beamof electrons.
 3. The apparatus according to claim 2, wherein thedirecting means comprises a system of lenses for directing the beam overthe entire surface of the substrate or ingot forming element.
 4. Theapparatus according to claim 3, wherein the system of lenses serves toapodize and expand the beam to apply an energy density that iscompletely uniform over the entire surface of the substrate or ingotforming element.
 5. The apparatus according to claim 2, wherein thegenerating means includes a pulsed diode type pulse accelerator fordelivering a beam of electrons that have a duration of less than 1 ns.6. The apparatus according to claim 2, wherein the directing meanscomprises a grid which expands the beam to cover the entire surface ofthe substrate.
 7. The apparatus according to claim 1, wherein thegenerating means comprises a laser.
 8. The apparatus according to claim1, wherein the generating means comprises a YAG or a neodymium-dopedglass laser suitable for delivering pulses that have a duration of lessthan 1 ns.
 9. The apparatus according to claim 1, wherein the generatingmeans comprises a sheet of solid lasers.
 10. The apparatus according toclaim 1, wherein the substrate or ingot forming element is bonded onto asupport to form a block and the directing means is configured to directthe energy pulse into the block.
 11. The apparatus according to claim 1,wherein the energy pulse of the generating means is a single pulse. 12.The apparatus according to claim 1, wherein the generating means repeatsthe energy pulse multiple times.
 13. The apparatus according to claim 1,wherein the substrate or ingot forming element comprises semiconductormaterial(s), LiNbO₃, LiTaO₃, or a composite material thereof.
 14. Theapparatus according to claim 13, wherein the substrate or ingot formingelement comprises silicon, SiC, GaAs, InP, GaN, SiGe, Ge, LiNbO₃,LiTaO₃, or a composite material thereof.
 15. The apparatus according toclaim 1, wherein the weakened zone is a porous zone.
 16. The apparatusaccording to claim 1, wherein the weakened zone is formed by deposition.17. The apparatus according to claim 1, wherein the weakened zone isformed by implantation.
 18. The apparatus according to claim 17, whereinthe implantation is of phosphorus, arsenic, protons, or rare gas ions.